Rubber covered roll



April 29, 1952 J. ROCKOFF RUBBER COVERED ROLL Filed Jan. 18, 1947 M w I M W W W W 1 M w M I w w p x kw ATTO R N EYS INVENTOR JOSEPH ROCKOFF Patented Apr. 29, 1952 RUBBER COVERED ROLL Joseph Rockoff, Dayton, Ohio, assignor to The Dayton Rubber Company, a corporation of Ohio Application January 18, 1947, Serial No. 722,802

This invention deals with coverings for rolls, in particular for rolls used for offset printing and textile machinery such as slasher rolls. Sponge rubber in such rolls is new, and in particular the use of a very thin sponge layer thereon. The sponge rubber provides for a good liquid control action and also for a high absorptive capacity both of which are essential in the case of offset printing rolls, such as form dampers and damper ductors used on ofiset lithographic presses and slasher rolls.

It is an object of this invention to provide coverings for rolls which are made of sponge rubber with a very fine and uniform texture.

It is another object of this invention to provide coverings for rolls which show a high degree of porosity.

It is another object of this invention to provide coverings for rolls which, in spite of the high degree of porosity, are of considerable stability and rigidity so that deformation during operation does' not occur.

It is still another object of this invention to provide coverings for rolls which have an extremely long service life.

I It is still another object of this invention to provide coverings for rolls which have a high absorptive capacity for liquids.

It is still another object of this invention to provide coverings for slasher rolls with which the amount of sizing material on the yarn may be controlled easily.

It is still another object of this invention to provide coverings for rolls from sponge rubber which may be thoroughly cleaned without difficulty.

These and other objects are accomplished by constructing a roll covering so that it has an inner bulk layer of solid rubber or rubber-like material and a more or less thin surface layer of sponge rubber with fine interconnected pores of uniform size.

The invention will be more 'fully understood from the following description taken in connection with the accompanying drawings, in which:

Figure 1 is a perspective view of a roll covering of my invention as mounted on an axle shaft;

Figure 2 is a longitudinal section taken along line 2-2 of Figure 1; and

Figure 3 is an enlarged fragmentary longitudinal section from which the shape and arrangement of the pores is more clearly recognizable.

Referring to the drawings in detail, the reference numeral 4 indicates an axle shaft on which 3 Claims. (Cl. 154-43) 2 a covering, generally designated with 5, is mounted. This covering 5 comprises an inner bulk layer 6 made of solid rubber or rubberlike material and an outer thinner sponge'lay'er'l. It is obvious (Fig. 3) that the outer sponge layer I consists of rubber material 8 and pores 9 uni formly distributed therein. These pores 9 are interconnected and of relatively regular size. This feature of the pores being interconnected is of the utmost importance, since by this the efficiency of the roll covering is greatly enhanced. Even the pores located at the innermost layer of the sponge section are accessible to the material to be treated and consequently the absorptive capacity of the entire unit is increased.

The covering of my invention is made by first arranging solid rubber material onto a mandrel in a thickness desired of the bulk'rubber layer, vulcanizing said layer, thereafter preparing a mixture of rubber, or rubberlike material, and crystals of a water soluble salt and applying said mixture over said solid rubber layer. The builtup unit is then again vulcanized, preferably after being wrapped in a wet cloth whereby the layers become integrally united. After vulcanization, the cover is groundto the precise size and surface condition desired. Thereafter the salt is removed by leaching it out with water. This leaching process is preferably carried out under pressure, for example under a pressure of approximately 200 lbs. per square inch. In order to obtain, after leaching, pores that are interconnected and thus to make possible that the surface layer in its entire thickness may be utilized, a relatively great amount of salt crystals is incorporated into said surface layer. It is evident that the degree of porosity may be adjusted 'by merely varying the amount of salt added. I have obtained very satisfactory results with 200 to 300 parts by weight of salt per parts of rubber or rubberlike material, but it will be understood that the particular proportions of salt and rubber are widely variable depending upon the texture.

Instead of grinding the surface prior to leaching, the salt crystals may also be removed first and then the covering be surface-conditioned by grinding. In this case it is advantageous, though not obligatory, to dry the unit prior to grinding.

The method of manufacturing the roll coverings described forms the subject of my co-pending application Serial No. 722,304, filed January 18, 1947, now Patent No. 2,500,573 granted March 14, 1950.

Various kinds of rubber materials are usable for the object of my invention. Natural as well as synthetic rubbers are operative, the selection being dependent upon the use intended for the covering. Synthetic rubbers which were found satisfactory for my purpose are the neoprenes, butadiene copolymers, such as butadiene acrylonitrile copolymer and butadiene styrene copolymer, and the polysulfide rubbers known under the trade-name Thiokol. Filler materials, vulcaniz ing agents and other auxiliary substances known may be added to the rubber materials. The term rubber as used herein therefore includes natural rubber as well as synthetic rubberlike materials of the types represented by the chloroprene polymers, such as Neoprene; butadiene copolymers, such as butadiene-acrylonitrile andbutadiene-styrene; and the polysulfide rubbers, such as Thiokol.

As the pore-creating salt, any water soluble salt is usable which does not decompose or disintegrate at the vulcanization temperature. For in stance, sodium chloride, various kinds of sulfates, sugar and others obvious to those skilled in th art may be used.

It will be understood that the thickness of the outer sponge layer is dependent upon thesize of the covering and upon the purpose for which it isintended. In the case of slasher rolls, a thickness of 1 to 2 inches was preferred for the bulk layer and'of to of an inch for the finished outerv layer. Similarly the hardness of the material also has to be adjusted according to the purpose intended. A hardness of from 40 to 60 on the Shore scale A was found the optimal range for slasher rolls. 7

In the following one exampl which was found very satisfactory for the roll ofmy invention is given without-the'intention of limiting the invention thereto.

Example ((1) Compound for the inner bulk layer:

100 parts by weight neoprene type GN parts by weight Zinc oxide 10 parts by weight cumar resin 5 parts by weight rosin oil 10 parts by weight mineral oil 10 parts by weight light calcined magnesium oxide 50 parts by weight f actice 1 part by weight Agerite (parabenzyloxy phenol) (b) Compound forthe sponge layer:

100 parts by Weight neoprene type GN 30 parts by weight clay 1 part by weight Agerite powder v 0.50 part by weight benzothiazyl disulfl'de parts by weight mineral oil 10 parts by weight light calcined magnesium oxide 10 parts by weight zinc oxide v 300 parts by weight crystallinesodium chloride It will. be obvious that by the specific method of preparing the spongerubber layer on the coveringsof my invention an article is obtained which has an extremely uniform texture and-in which the holes are interconnected. These interconnected holes or pores form channel-like voids which have a considerablyhigher suction than have small individual pores; as a result thereof a greater absorbability is obtained. Due to the inner solid bulk layer, the rigidity and form-stability of the covering are considerably greater than if it were made entirely of sponge rubber. This feature of having only the outer layer made of sponge rubber facilitates cleaning of the channels in case this should become necessary, since the innermost ends of th channels are better accessible to the cleaning means. Furthermore, due to the uniform size and distribution of the cavities, the operation of the covering is more uniform at its various locations.

It will be understood that although a number of uses for the articles of my invention have been set forth, these represent merely examples, since there are a great many other possibilities for which the invention is, or might become, of value.

It will also be understood that while there have been described herein certain specific embodiments of my invention, it is not intended thereby to have it limited to or circumscribed by the specific details given in View of the fact that thisinvention is susceptible to various modifications and changes which come within the spirit of this disclosure and the scope of the appended claims.

I claim:

1. A rubber covered roll for the application of liquid materials having substantial stability and resistance to deformation during use, and having a surface possessed of a high degree of porosity, a uniform texture, and a high absorptive capacity for liquids, which comprises a shaft, a solid inner bulk rubber layer surrounding said shaft and mounted thereon, and an outer sponge rubber layer surrounding and integrally united with said inner layer, said outer layer being of less thickness than the inner layer, said outer layer having uniformly distributed therethrough a multitude of channels formed of interconnected uniformly distributed minute pores, said pores conforming in shape to granules of finely divided water soluble material incorporated in said outer layer in the proportion of at least twice as much soluble material by weight as rubber and removed therefrom by leaching.

2. A rubber covered roll according to claim 1 wherein the water soluble material is crystalline sodium chloride.

3. A rubber covered roll according to claim 1 wherein the outer layer is composed of a butadiene copolymer type of synthetic rubber.

JOSEPH ROCKOFF.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,365,606 Seymour-Jones Jan. 11, 1921 1,370,709 Smith M212 8, 1921 1,555,389 Stevens Sept. 29.1925 1,563,943 Adams et a1 Dec. 1, 1925 1,659,371 Merrill Feb. 14, 1928 2,006,364 Morse July 2, 1935 2,353,877 Chollar July 18, 1944 2,427,765 Chollar Sept. 23, 1947 2,427,836 Chollar et a1. Sept. 23", 1947 2,467,213 Luaces Apr. 12, 1949 2,500,573 Rockoff Mar. 14, 1950 

